Collaring the bitch... Or rather, fish.

"I see. So you're that kind of person, huh?" Natsu stated

"Excuse you? Who exactly are you?" She hissed, noticing Lucy's current state of being, and Natsu's position

"Oooh no. I see what's going on here! I will not allow you to defile this young lady--" she began, before immediately being silenced. Her eyes did a sort of reverse cross, before she fell to the floor, beginning to flop and flail wildly

Natsu looked at what he wrote

"If Aquarius ever considers hurting, or disobeying Natsu Drangeel, she will instantly believe she is a fish until Natsu says 'Off the hook'"

"Natsu what did you, like, do to her? Why's she all like, floppy?"

"Because she's a fish, Lucy... Aquarius, I know you can still understand me. So listen well. I'm gonna set some ground rules for our little relationship here."